SEMICONTINUOUS ETHANOL FERMENTATION WITH SHOCHU DISTILLERY WASTE*

An effective utilization system using distillery waste discharged from Japanese traditional shochu factory was developed. Mugi (barley) shochu distillery waste discharged from a novel vacuum distillation procedure (35–40°C) contained a large number of viable yeast (7 × 10⁶ cells/ml), glucoamylase activity (19.7 units/ml), acid protease activity (940 units/ml), and neutral protease activity (420 units/ml). Ethanol fermentation was achieved with a mash composed of glucose as the sola carbon source and mugi shochu distillery waste. After ethanol fermentation was completed the fermented broth was again distilled at 35–40°C in vacuo and the non volatile residue used in the next ethanol fermentation. In this way, semicontinuous ethanol fermentation system of more than 10 cycles was developed. Even in the distillate of the mash of the 8th fermentation cycle, 7.9% of ethanol, 33.0 ppm of ethyl acetate, 28.5 ppm of isobutyl alcohol, and other aromatic compounds were present. A semicontinuous ethanol fermentation system has been developed for shochu distillery waste which conventionally is treated as wastewater.     

ETHANOL FERMENTATION OF VARIOUS RED RICES WITHOUT COOKING

With various red rices as raw material, fermentation without cooking was allowed to proceed at pH 4.0 and 30°C for 4 d for production of novel alcoholic beverages. Ethanol fermentation was achieved with various rice grains. In particular, uncooked wild-rice (Zizania aquatica) is reported now for the first time as being used for ethanol fermentation. The final concentration of ethanol achieved during fermentation was 8.8–9.3% (v/v). Rice wine made from aromatic red rice (Oryza sativa var. Indica, Tapol) had a wine-like red color. It was rich in a fruity aroma and had a characteristic sour taste, as revealed by organoleptic testing. Volatile substances formed have been analysed by gas chromatography. Rice wine made from black rice (Oryza sativa var. Indica) also had a wine-like red color and a sour taste. By contrast, rice wines made from red rice (Oryza sativa var. Japonica) and wild-rice were faintly yellow in color and had a sake-like and a somewhat green tea-like flavor, respectively. Although the red pigments of the aromatic red rice and black rice were solubilized during uncooked ethanol fermentation, the pigments of red rice and wild-rice were insoluble and not available as material for brewing of red-colored alcoholic beverages. Aromatic red rice appears to be a suitable material for the production of a wine-like alcoholic beverage.     

EFFECTS OF THE COOKING PROCESS ON THE CHARACTERISTICS OF AROMATIC RED RICE WINE

Fermentation tests were performed with cooked and/or uncooked, polished aromatic red rice (Oryza sativa var. Indica, Tapol) and aromatic red rice bran using compressed baker's yeast and a preparation of glucoamylase produced by Rhizopus, sp. as saccharifying agent. The quality in terms of both aroma and taste of the red rice wine made with uncooked, unpolished aromatic red rice was much higher than that of rice wine made with cooked, unpolished aromatic red rice. However, the bran fraction of aromatic red rice was fairly resistant to the cooking process and this fraction was hardly affected or degraded by the cooking process. Furthermore, the bran fraction improved the quality of rice wine made from mash that contained cooked, polished rice which had a rather lower-quality aroma. In red rice wine brewing, the polished rice fraction of aromatic red rice may suffer from undesirable effects during the cooking process.     

EFFECTS OF PROTEOLYTIC ACTIVITY ON THE CHARACTERISTICS OF AROMATIC RED RICE WINE

The quality of rice wine made from uncooked, unpolished aromatic red rice grain was improved by use of a commercial preparation of acid protease from Aspergillus niger during ethanol fermentation. The fermentation rate of the mash which contained the acid protease was much higher than that of mash that did not contain the preparation of acid protease. The rice wine made from uncooked, polished aromatic red rice, which usually had a less acceptable aroma, was improved by use of the preparation of acid protease, and large amounts of isobutyl alcohol, n-propyl alcohol and ethyl acetate were detected in the resultant rice wine. By contrast, the quality of rice wine made from the bran fraction of aromatic red rice was not improved by the preparation of acid protease. The polished rice fraction of aromatic red rice was affected by the acid protease and the aromatic quality of the rice wine was improved. The aromatic characteristics of red rice wine made from cooked, unpolished aromatic red rice grains, which was rather inferior in terms of both aroma and color, were also improved by the addition of the preparation of acid protease during ethanol fermentation. Thus acid protease has beneficial effects on the production of aromatic red rice wine.     

PRODUCTION AND CHARACTERISTICS OF RED RICE SAKE

Red rice sake was efficiently produced from unpolished red rice without cooking by use of rice koji prepared with shochu koji mold, Aspergillus kawachii, as saccharifying agent. A comparative study was made of red rice sake made with rice koji and red rice wine made with a preparation of glucoamylase known as Sumizyme. Red rice sake contained about 13% ethanol and its acidity was 8.6. Large amounts of volatile compounds, such as isobutyl alcohol and ethyl acetate, were found in the red rice sake. The red color of the red rice sake was more intense than that of the red rice wine. The quality of red rice sake was better than that of red rice wine, as assessed by gas chromatography, spectrophotometric analysis and organoleptic testing. In accordance with the traditional method for sake brewing, red rice, rice koji and tap water were added to the initial mash. The red color of the red rice sake made with these additions was more intense than that of red rice sake made without these additions. The rice wine was somewhat improved by these additions, as assessed by organoleptic testing. The body of the resultant rice wine was fortified with dextrin and its mild characteristics were derived from sugar and dextrin.     

米糠多糖的提取工艺及其生物活性的研究进展

米糠多糖是指从稻糠中提取纯化的一种以α-1，6-糖苷键为主要结构的多糖。由于它在抗肿瘤、免疫增强、抗细菌感染及降血糖等方面具有较高的生物活性，近几年有关米糠多糖的研究已成为一个研究热点。主要综述米糠多糖的分离提取、种类以及其生物活性，并就其开发研究中存在的问题和研究前景做一探讨。     

EFFECTS OF β-GLUCOSIDASE ACTIVITY ON THE CHARACTERISTICS OF AROMATIC RED RICE WINE

The pigment in the bran layer of aromatic red rice (Oryza sativa var. Indica, Tapol) is rather stable, has a characteristic red color just like that of grape wine and has a peak of absorbance at 530 nm at an acidic pH. A commercial saccharifying agent, glucoamylase AN-2, produced by Aspergillus niger was fractionated to separate glucoamylase and β-glucosidase activities by column chromatography on CM Sephadex C-50. The red rice wine made from uncooked, unpolished aromatic red rice using the fractionated, β-glucosidase-free preparation of glucoamylase had a characteristic red color. By contrast, red rice wine made with glucoamylase AN-2, which contained β-glucosidase activity, was inferior in color. The red pigment of aromatic red rice wine was decolorized and glucose originating from the red pigment was released by enzymatic digestion with the fractionated preparation of β-glucosidase. The partial decolorization of aromatic red rice wine was ascribed to the enzymatic action of β-glucosidase that was present in glucoamylase AN-2. Thus β-glucosidase activity has an undesirable effect on the brewing of aromatic red rice wine.